Boxmaking machine



June 29, 1954 E. L. BIVANS ,68

BOXMAKING MACHINE Filed Jan. 23, 1950 6 Sheets-Sheet l INVENTOR: ELBERT L. Ell ANS.

ATTORNEK June 29, 1954 E. L. BIVANS BOXMAKING MACHINE 6 Sheets-Sheet 2 Filed Jan. 25. 1950 INVENTOR: ELBERT L. Ell ANS.

ATTORNEY.

June 29, 1954 BWANS 2,682,209

BOXMAKING MACHINE Filed Jan. 25, 1950 6 Sheets-Sheet 5 A TTORNEK Filed Jan. 23 1950 June 29, 1954 E. BIVANS BOXMAKING MACHINE 6 SheetsSheet 6 hiya/5' INVENTOR: ELBERT L. Bil ANS.

A TTOR/VEK Patented June 29, 1954 BOXMAKING MACHINE Elbert Litton Bivans, Los Angeles, Calif., assignor to E. L. Bivans, Inc., a, corporation of California Application January 23, 1950, Serial No. 140,073

14 Claims.

The invention relates to a box making machine and more particularly to a machine which starts with a box of pasteboard which is folded flat, the adjoining sides of the box being glued together on a glue line and side flaps and an end flap with fold lines therein projecting from one end of the box, the top flap projecting from the other end.

The invention relates particularly to a machine to which is fed such collapsed box blanks, the machine functioning to open the box and to tuck the side flaps and the end flap in one end thereof, whereupon the empty box thus formed is ejected and the operation repeated.

The blanks are fed one at a time from the bottom of a stack of blanks, to a station where the various folding operations above described are performed. A feeding device slides the bottom blank from the stack and that blank in going forward ejects the completed box.

The collapsed box blank has an overall width which is greater than the open box, as one end and one side of the box blank lie substantially in a plane when the box is collapsed, thatis, folded along one edge of the front or back of the box. The invention takes this into account and provides an improved combined tucker for one of the side flaps and presser foot to press one side of the end flap against an end flap tucker, this device being operated for the purpose stated and also moved out of the way when a box is completed so as not to obstruct the admission of the next box blank into the flap folding mechanism. The two side flap tuckers are moved in and out in a horizontal direction in order to come into or out of position to tuck the side flaps. While it would be possible to increase the throw of these devices in order to get them out of the way for the purpose stated, this would necessitate a comparatively long throw. The side flap tucker devices operate only during a small part of the total cycle of operation of the machine, which means that their speed of operation is limited as the tucker devices come to a full stop and reverse their direction in a short interval of time.

An object of the invention is to overcome the limitation which the side flap tuckers impose on the speed of operation of the machine. This is accomplished by obtaining a shorter throw for these side tuckers by moving one of them out of the way by shifting it vertically with respect to its horizontal path of tucking movement.

A further object of the invention is to provide flap operating mechanisms which are adjustable, together with an adjustable throw for the feed and an adjustable magazine, whereby the machine may be readily adapted to handle boxes of various dimensions.

A further object of the invention is to provide an improved power drive for various flap operating mechanisms and for the feed. The improvement consists in arranging this power drive in the form of a sub-assembly whereby it can be handled as a unit for assembly or for repair.

A further object of the invention is to provide an improved power drive which is adjustable to vary the length of the throw of the device for feeding the blank from the stack at the supply station to the folding station.

Fig. l is a perspective view of a box making machine according to the present invention.

Fig. 2 is an enlarged perspective view with parts broken away.

Figs. 2 to 5 are perspective views with parts broken away showing the box and various flap folding devices in various operating positions.

Fig. 6 is a top plan view of the machine of Fig. 1 with the left end thereof broken away.

Fig. 7 is an enlarged perspective view of the feeding device and associated parts with parts broken away, the discharge end of the machine being at the left of this figure.

Fig. 8 is a perspective view with parts broken away, this view being farther toward the discharge end of the machine than the view in Fig. 7.

Fig. 9 is a vertical front elevation of the machine of Fig. l with the casing removed to show the operating mechanism. I

.Fig. 10 is a side view in elevation on line iil-l0 of Fig. 9, looking in the direction of the arrows.

Fig. 11 is an enlarged sectional view on line ll-Il of Fig. 10 looking in the direction of the arrows.

Figs. 12 and 13 are sectional views onlines of the corresponding numbers in Fig. 9 looking in the direction of the respective arrows.

Fig. 14 is a sectional view on line l l-i i of Fig. 13 looking in the direction of the arrows.

Fig. 15 is a sectional view on line l5l 5 of Fig. 9 looking in the direction of the arrows.

The box machine comprises a rectangular casing I mounted on rollers 2, see Fig. 10 so that it can be moved about. The casing I has a flat top 3, see Fig. 1, having a magazine 4 at a supply station for a stack ll of collapsed boxes like 5, as well as a folding station 6 where the collapsed box is shifted from a collapsed condition to an expanded open condition, and the side flaps i and 8 for the bottom and the bottom flap 9 are tucked in. The completed open box ready for ejection is illustrated at I8 in Fig. 1, while a new blank or collapsed box on its way from the bottom of the stack to the folding station 6 is indicated at II.

The blanks like are made of a sheet of paste board having a glue line 33, see Fig. 8, along longitudinal edge of the blank. As shown in Figs. 6 and 8, the blanks 5 are folded substantially flat with the front (or back) I2 of the box and adjoining side I3 lying substantially in a plane on top of the back (or front) I4, and the other side I5. The collapsed box blanks 5 are made by some other machine forming no part of the present invent-ion and as thus supplied they have fold lines at each longitudinal corner of the blank. The box is moved to open position, by the ma chine of this invention, by hinging it or swinging it by a folding bed 48, see Fig. l, to bring the front and back i2 and I4 perpendicular to the sides I3 and I5, as shown in Figs. 1 and 8. The machine of the present invention does not operate on the side flaps or end flap at the open end I6 of the box. The empty box I3 as it leaves the machine of the present invention is thus ready to be filled by hand or by some other machine.

The collapsed box blanks 5 as obtained from the supplier and as fed into the machine of the present invention have a bottom flap 9, see Fig. 6, which lies in the same plane as the back I4, the flap 9 having a fold line at its juncture with the back I3, this fold line being similar to the fold line shown at 2I in Fig. 6 for the flap 3! at the open top of the box.

Also the side I3 has a side flap 9 which lies in a plane with the side I3 and is provided with a fold line 28. The opposite side I5 has a side flap 1 lying in its plane and having a fold line like fold line 29. The open end I5 of the blank has an end flap 22 and side flaps 23, 24, see Fig. 8.

The blanks 5 are stacked in the magazine l so that the flap 3 which forms the bottom of the closed box is lowermost against the guideway '32 in which the blanks like 5 travel from the "magazine A. to the folding station 6, with the result that the flap 22 at the open end of the box, see Fig. 8, overhangs the rear edge l8 of the back It and advantage is taken of this in feeding the blanks 5 from the bottom of the stack as follows.

As shown in Figs. and 11, the feed device i5 is in the shape of a fork having a forwardly extending long upper arm 26 and a shorter lower arm 21 with a notch 28 therebetween. The back throw of the feed device I9 is limited to a position wherein the upper fork 2B underlies the flap 22, with the notch 28 withdrawn from the edge I8, so that on the forward stroke of the feed device IS, the edge I8 is caught in the notch 28 which pushes the blank 5 forwardly in the guideway 32. The weight of the stack I1 urges the bottom blank 5 in the stack on to the feed device I9.

As shown also in Fig. '7, the upper arm 26 of the feed device has a shoulder 34 which forms the notch 28 above referred to, to engage the edge 18 of the box blank. The lower arm 21 of the feed device is in the form of a runner bar having spaced holes 33 to receive a screw 35 which passes through an elongated slot 35 in the arm 25. While the limit of the back throw of the feed device I9 can be adjusted by means of a quadrant 58 shown in Fig. 10, a refinement of this adjustment is made possible by the parts just described, as the arm 26 can be adjusted on the runner bar 21 within the limits of the length of the slot 35 and then the bolt 35 can be engaged with another hole like 33 to obtain further adjustment.

As shown in Fig. l, the runner bar 21 travels along the opening 31 between two strips 38 and 39 which forms the bed of the guideway 32 for the blank 5. The edges of the guideway 32 are defined by strips 4| and 42 which can be adjusted various distances apart by means of screws like 43 and slots like 44 in the top 3.

The runner bar 21 at its forward end need not engage the bottom of the box blank 5.

As shown in Figs. 10 and 11, the runner bar 21 is carried at the top of an arm 16 on a bracket 11 having a tubular bearing 45 which slides on a stationary rod 46 supported at opposite ends of the frame 41 of the machine as indicated at 48 and 49. As shown in Figs. '7 and 11, parallel to the rod 46 which serves as a slide bearing for the feed device I9 is a rectangular rail I43 suitably carried by the main frame 41 as indicated at I44. Bracket 11 has fixed thereto by a screw I45 an oil impregnated bronze block I46 having a groove I41 in one side thereof to fit and slide on the rail I53, to stabilize the travel of the feed device I9. Fixed to the bracket 11 is a forwardly extending arm 5I connected by a link 52 to the upper end of an oscillating lever 53 pivotally supported to the bottom of the frame 41 as indicated at 54. Carried by the lever 53 is a quadrant having a slot 55 for a bolt 55 at the rear end of a connecting rod 51. By loosening the bolt 55, the point of attachment of the connecting rod to the quadrant 59 may be varied as desired, in order to vary the back throw of the feed device IS. The forward end of the connecting rod 51 is connected to an eccentric 58 having a shaft as indicated at 59. The quadrant 50 is the arc of a circle which is concentric with the axis of shaft 59 when the connecting rod 51 is on dead center as shown, with the result that the limit of the forward stroke of the feed device I9 is also substantially the same, for various lengths of stroke as adjusted by various points of attachment of the rear end of connecting rod 51 in the quadrant 50. For the particular quadrant adjustment shown in Fig. 10, the full lines show the feed device at the limit of its forward stroke, while the dotted lines associated with Bil show the quadrant and associated parts at the limit of its back stroke.

The shaft 59 is driven by a pulley 18 connected by various other belts and pulleys indicated at EI to an electric motor 62 suitably supported at the bottom of the frame 41. Also mounted on shaft 59 are (l) cam 53, see also Fig. 15, which operates a roller 64 on an oscillating arm 85 connected by a link 65 to a bell crank 61 which operates the side tuckers 68 and 89 in and out in a horizontal direction to tuck the side flaps 1 and 8, (2) a cam 10, see also Fig. 12, which acts on a roller TI on an oscillating arm 12 connected by a link 13 to the end tucker 14 which tucks in the bottom flap 9, and, (3) a cam 80, see also Fig. 13, which acts on a roller 8| mounted on an arbor 82 which also carries a roller 83, arbor 82 being carried by an arm 84 fixed to a slide 85 which moves the side tucker 69 up and down at certain times to get it out of the way of a new blank 5, roller 83 acting in a split bearing 86 on an oscillating arm 81 connected by a link 88 to the folding bed 48.

Shaft 59 has a bearing support in a sub-frame 90, see Fig. 9, removably attached to the uprights like 9| of the frame 41 by bolts like 92. The subframe 90 may be bolted or welded to the frame 41. In any event, the construction shown simplifies the manufacture of the device by having a unit assembly of the shaft 59 and its various attachments above described.

As shown in Fig. 12, spring 93 holds roller 'II on cam I0. As shown in Fig. 13, spring 94 holds roller 8| on cam 80. As shown in Fig. 9, spring 95 acts on bell crank 61 to hold roller 04 on cam 63.

As shown in Fig. 9, side tucker 58 is in the form of a horizontally extending plate carried by a bracket 96 adjustable at various positions on a tube 91 to which it is secured by a screw 98. Tube 91 has a rib 99 to prevent bracket 95 from rotating. Tube 9'! slides on a rod I which serves as a slide bearing. Bell crank 61 has a link connection IOI with the tube 9! as indicated at hinge I02. The hinge connection I02 is on a bracket I39, see Fig. 9, fixed toone end of tube 91. Bracket I 39 has a laterally extending arm I40 which slides in a track I II on the sub-frame 90, to insure that the side flap tucker 58 will move in a straight line. Link IIlI is arranged on one side of the pivot axis I 03 of the bell crank 61. On the other side of axis I93 is a link I34 connected to the intermediate point of an oscillating arm I05 having a pivotal connection at its lower end as shown at I05 with the slide 85. Slide 85 slides up and down on a vertical rod I5 which serves as a slide bearing.

When cam 63 operates to raise link 66, this operates bell crank 61 to move the side flap tuckers 68 and 69 toward each other to tuck in the side flaps, and when cam 63 operates to permit spring 95 to swing bell crank 6! in a reverse direction, this moves the side flap tucker 98 and 69 apart. Referring particularly to Fig. 1, the folding bed :40 has a hinge I01 having a longitudinal axis coincident with the fold line between the side I5 of the blank 5 and the back IA of the blank. Opposite the folding bed 40 is a butt plate I08 against which the side I3 of the blank 5 abuts when the folding bed 40 swings to an upright position to expand the blank into a box. The box is restrained from rising, by means of a shelf I09 on the folding bed 40 and a similar shelf IIO on the butt plate I98. The butt plate I08 is carried by the strip 42 and adjustable with it to accommodate boxes of different widths. The shelves I09 and H0 are also adjustable along their respective supports by means of a slot like III and screw like II2, to accommodate boxes of different depths. At the outer end of the guideway 32 in front of the hinge I07 for the folding bed 40 is a shelf I42 which supports one edge of the blank 5 when it is at the folding station 6. The runner bar 21 at its outer end is of reduced width so that it will pass the shelf IE. The box blank 5 is pinched or squeezed between the shelf I 42 and the folding bed 40 and its shelf I09 when the folding bed 40 swings upwardly.

The magazine 4 has posts like H5 and I I9 arranged at the periphery of the stack I'I, these posts being carried by strip 4I, similar posts like I I! being carried by strip 42. Strips ll and 42 are adjustable as above described by slots and screws like 34 and 35 to accommodate blanks of different sizes. In making an adjustment for blanks of different sizes, it will be noted that the hinge I0! is not adjusted, but is a fixed reference line or axis with reference to which the necessary other items are adjusted.

As shown in Fig. 12 the end tucker M has a pivotal support I I3 on a horizontal axis. In order to push the end flap 9 into the end tucker i l at the time that it is operating to form and tuck in the end flap 9, as shown in Figs. 1 to 5, associated with the side flap tucker 59 is a presser foot in the form of a pin H8, 2. similar presser foot I I9 being associated with the side flap tucker 68. The presser foot H8 is adjustable by means of a screw I29 in an elongated slot I2I in an arm 22 rotatably carried by a stud I23. The presser foot I I8 is urged to swing out, by a spring I24 and its arc of movement is limited by a lug I25, see Fig. 13, on arm I22 striking a stop I29 on arm I95. Arm I05 swings behind a guide plate I27. Guide plate I2? is mounted on an arm I36 fixed to the tubular slide 85 and the outer end I31 of arm I30 rides in a vertical slot in a brass plate I30 fixedon the sub-frame 90. Presser foot I I9 is similarly mounted and is urged by spring I29 to swing out. As bell crank 91 operates to bring the side flap tucker 98, 69 together, assuming a fresh blank like 5 is at the folding station 6, and assuming that the folding bed 49 has operated to expand the blank 5 to its rectangular form, the side flap tuckers 63 and 69 advance to fold in the side flaps T and 9 and at the same time the presser feet IE3 and II9 are moved to a position above the flap 9 so that on subsequent upward movement of the end flap tucker M, such movement is bucked against the force of springs I24 and I29 so that the presser feet I I3 and I I9 form a yielding abutment to restrain the end ilap 9 so that the end tucker I l will embrace it. Just before the end flap tucker I9 reaches its vertical andfinal position, the bell crank 97 operates to remove the presser feet H9 and H9 and the end flap tucker I' l continues its movement to a vertical position to complete tucking in the end flaps 9. Thereafter, the camv operates to open up the folding bed 99 to swing it from a vertical to a horizontal position, and simultaneously lower the side flap tucker 99 and presser foot II8, to get them out of the way so that the fresh blank 5 can be fed into the folding station 6.

In order to revent the end flap tucker M from pushing the box back along the slideway 32 out of the folding station 9, as shown in Figs. 7 and 8, the slideway 32 is provided with a stop device I29 having a forwardly facing shoulder I99 against which the edge I 8 of the back I I abuts. The front of the stop device I29 has an incline I3! so that the back it of the blank will ride over it. Also referring to Figs. '7 and 8, to prevent the flap I32 of a fresh blank 5 from telescoping with a completed box I0, the guideway 32 also has, in front of the stop I29, and at one side of the guideway 32, an inclined lug I33 which tilts up flap I32 so that it will contact and cross the side flap 2 1, see Fig. 8, at the open end of a finished box to engage the same and push it out so that it will drop into a chute I34, shown in Fig. 1. To limit this tilt movement of flap I32 above the inclined lug I33 is provided a stop shelf I35.

In Fig. 2 the feed device I9 has brought a new blank 5 into position for folding and that blank has ejected the finished box. In Fig. 3, the folding bed 59 has moved to an upri ht position, and this by the way, squeezes the box against the butt plate I08 which squeezing action together with the stop I29 shown in Fig. '7 prevents the blank box from being dragged out of position by the feed device is on its return stroke. Fig. 4 shows the blank 5 held in its rectangular form, the side flap tuckers 68 and 68 having moved in to tuck the side flaps and the presser feet H8 and H9 having been moved into position in front of the end flap 9, the end flap tucker '14 having been swung partly up into position to embrace the end flap Q under action of the presser feet H8 and H9. After further movement of the end flap tucker M, as above stated, the presser feet H8 and H9 and their associated side flap tuckers 69 and 58 respectively are withdrawn, whereupon the end flap tucker completes its upward movement to tuck in the end flap 2.

The box making machine illustrated herein has been constructed and operated and found to have the advantages above set forth.

Various modifications may be made in the invention without departing from the spirit of the following claims. For example, the axis of the hinge H31 of the folding bed 48 can be arranged at the other side of the guideway 32 for box blanks which are made in such a manner as to require opening up in that manner. This type of machine has also been constructed and operated.

I claim:

1. A box making machine comprising a hinged bed for opening a collapsed box, an opposed butt plate, means for varying the separation of said butt plate from the hinge axis of said hinged bed to accommodate boxes of different Width, separate angular abutments on said hinged bed and on said butt plate, separate means for adjusting said abutments to different positions to fit boxes of different depth, a tucker adjacent said hinge axis for 'ucking one of the side flaps of the box, an opposed tucker for tucking the opposite side flap of the box, a reciprocating drive for said last mentioned tucker, means for adjusting the position of said last mentioned tucker with respect to its said drive to adjust the distance thereof from said hinge axis to accommodate boxes of various widths, means for reciprocating said first mentioned tucker in a path for tucking operation, and means for periodically moving said last mentioned tucker out of its tucking path out of the way to permit a new box blank to be fed to said folding station,

a reciprocating feed device for transferring a box blank from the bottom of said stack to said folding station, means for varying the throw of said feed device to accommodate boxes of different lengths, a feed magazine at said supply station, means for adjusting the length and breadth of said magazine to accommodate blanks of different sizes, an end flap tucker, a presser foot device on each of said side flap tuckers for pressing the end flap into engagement with said end iiap tucker and separate means for adjusting the position of each of said presser foot devices to suit end flaps of difierent sizes.

2. A box making machine comprising a reciprocating feed device, an eccentric for driving said feed device, side flap tuckers, a bell crank having a link connection with each of said side flap tuckers for reciprocating said tuckers, a cam for operating said bell crank, an end flap tucker, a cam for operating said end flap tucker, means supporting one of said side flap tuckers for movement transversely of its path of tucking movement, a cam for operating said last mentioned means, a shaft supporting said eccentric and said three cams, said machine having a frame, means removably supporting said shaft on said frame, and means for driving said shaft.

3. A box making machine according to claim 2 comprising a folding bed having an operative connection with said third mentioned cam.

4. A box making machine comprising a horizontal blank feed, an upright rod slide bearing, a tube slidable thereon, a bracket having a side flap tucker thereon, means for pivotally connecting said bracket to said tube, a bell crank having a link connection with said bracket and cam means for operating said bell crank.

5. A box making machine comprising a supply station for a stack of collapsed boxes, a box opening and flap tucking station, a reciprocating slide feed device for transferring a collapsed box from said supply station to said other station, and means for adjusting the throw of said feed device without substantially varying the outer limit of that throw adjacent said other station, said means comprising an oscillating lever, a link connecting said lever and said feed device, said lever having an arcuate slot, a connecting rod having an outer end, and means for adjustably connecting said outer end at various positions along said slot, said connecting rod having an inner end connected to said eccentric, said slot being concentric with the axis of said eccentric when said connecting rod is on dead center.

6. A box-making machine comprising a folding station having a stationary upright plate, a hinged plate having a hinge axis spaced from said stationary plate the width of the front of an open box, means for feeding a folded box between said plates and overlying said hinged plate, means for operating said hinged plate to upright position to open said box, said box having an end flap and side flaps, an end flap tucker, a side flap tucker adjacent said stationary plate for tucking the corresponding side flap, a side flap tucker adjacent said hinged plate for tucking the corresponding side flap, means for operating said side flap tuckers back and forth in a tucking path, means for moving said secondmentioned side flap tucker transversely of said path into or out of position in front of said hinged plate, and means for operating said end flap tucker.

7. A box-making machine comprising a folding station having a stationary upright plate, a hinged plate having a hing axis spaced from said stationary plate the width of the front of an open box, means for feeding a folded box between said plates and overlying said hinged plate, means for operating said hinged plate to upright position to open said box, said box having an end flap and side fiaps, an end flap tucker, a side flap tucker adjacent said stationary plate for tucking the corresponding side flap, a side flap tucker adjacent said hinged plate for tucking the corresponding side flap, a spring pressed presser foot of each of said side flap tuckers for said end tucker, a cam means for operating said side flap tuckers back and forth in a tucking path,

' another cam means for moving said second-mentioned side flap tucker transversely of said path into or out of position in front of said hinged plate, and other cam means for operating said end flap tucker.

8. A box-making machine comprising side flap tuckers, an end flap tucker, a stationary plate and a hinged plate, means comprising a cam for operating said side flap tuckers along a path, means comprising a cam for operating said end flap tucker, and means comprising a cam for operating said hinged plate and for shifting one of said side flap tuckers transversely of said path into and out of position in said path adjacent said hinged plate.

9. A box-making machine according to claim 8 comprising a shaft for said three cams, and means for driving said shaft.

10. A box-making machine comprising side flap tuckers movable back and forth along a horizontal tucking path, cam means for operating said tuckers along said path when in juxtaposition, and independent cam means for moving one of said tuckers vertically into and out of said path.

11. A box-making machine having a folding station, means for feeding a collapsed box to said station along a path, an upright slide bearing, a slide therefor, a side flap tucker having a pivotal support on said slide, said pivotal support supporting said tucker for vertical movement of said tucker into and out of said path, cam means for oscillating said tucker, and independent cam means for operating said slide to raise said tucker into or lower the same out of tucking position, respectively.

12. A box-making machine comprising a folding station having means for folding a box from collapsed state to open state, said box having side flaps and an end flap, a tucker for said end flap, a side flap tucker for each of said side flaps, each of said side flap tuckers having a stud, an outwardly extending arm rotatably carried by said stud, an inwardly extending presser foot carried by said arm, means for adjusting the position of said presser foot along said arm, spring means urging said presser foot toward said end fiap tuckers to said bell crank at one side of said axis, a link connecting the other of said tuckers to said bell crank at the other side of said axis, a cam follower having a link connecting with said bell crank, and a cam for operating said follower, said bell crank operating said tuckers in a path, a slide bearing extending transversely of said path, a slide on said bearing, one of said tuckers having a pivot carried by said slide, and independent cam means for operating said slide.

14. A box-making machine comprising a bed, means for moving a collapsed box along said bed, said box having an end flap projecting foremost therefrom, means at on end of said bed for expanding the box with its end flap projecting therefrom beyond said bed, means at said end of said bed for tucking the end flap into said box, and means for operating said expanding means to hold the expanded box during operation of said tucking means, means supporting said tucking means for movement from a lower position to an upper upright position, means for operating said tucking means, and means for ejecting the open tucked box over the top of said tucking means when said tucking means is in its lower position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 639,354 Butler Dec. 19, 1899 804,716 Gay Nov. 14, 1905 1,195,937 Wills Aug. 22, 1916 1,378,579 Bernotow May 17, 1921 1,397,552 Smith Nov. 22, 1921 1,494,977 Rose May 20, 1924 1,702,704 Phillips 1 Feb. 19, 1929 2,458,341 Cake Jan. 4, 1949 2,517,449 Shields Aug. 1, 1950 FOREIGN PATENTS Number Country Date 476,112 Germany May 10, 1929 

